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The Axial Skeleton

 



Skeletal system includes both:

      Axial skeleton

    Skull

    Auditory ossicles and hyoid bone

    Vertebral column

    Thoracic cage

      Appendicular skeleton

    Pectoral and pelvic girdles

    Upper and lower limbs

 

The skull

      Consists of the cranium and the bones of the face

    The cranium encloses cranial cavity

    Facial bones surround and protect the entrances to the respiratory and digestive tracts

      Superficial landmarks include the sutures

    Lambdoid

    Coronal

    Sagittal

    Squamous

 

Focus: The Individual Bones of the Skull Cranial Bones

      one occipital bone

    foramen magnum

      two parietal bones

      one frontal bone

    frontal sinuses

 

The Axial Skeleton

 

 

Facial bones

      Maxillary bones

      Mandible

      Palatine bones

      Nasal bones

      Vomer

 

Maxillae

      Largest facial bones

      Form the upper jaw and most of the hard palate

 

Palatine and Nasal Bones

      Palatine bones

    Small L shaped bones

    Form the posterior hard palate and floor of the nasal cavity

      Nasal bones

    Superior border of external nares

 

Vomer, Zygomatic and Lacrimal bones

      Vomer

    Inferior portion of the nasal septum

      Zygomatic bone

    Temporal process articulates with zygomatic process of temporal bone

      Lacrimal bones

    Smallest bones of the face

    Sit medially in orbit

 

Mandible and Hyoid bones

      Mandible

    Bone of the lower jaw

      Hyoid

    Suspended by stylohyoid ligaments

    Supports the larynx

 

The orbital and nasal complexes

      Seven bones in the orbital complex

      Nasal complex = bones that enclose the nasal cavities and paranasal sinuses

 

Skulls of infants and children

      Fontanels permit skulls of infants and children to continue growing

 

 

Vertebral column

      Vertebrae, sacrum, coccyx

    7 cervical vertebrae

    12 thoracic vertebrae

    5 lumbar vertebrae

    Sacrum and coccyx are fused vertebrae

 

Spinal curvature

      Four spinal curves

    Primary (accommodation) curves = thoracic and sacral

    Secondary (compensation) curves = lumbar and cervical

 

Vertebral anatomy

      Typically has a body and vertebral arch

      Superior and inferior articular processes

      Separated by intervertebral discs

 

Vertebral regions

      Cervical

    Has distinctive shape

    Large relative size of vertebral foramen

    Costal processes with transverse foramina

    Notched spinous processes

 

Thoracic vertebrae

      Heart-shaped body

      Long slender spinous processes

      Articulations for ribs

 

 

Lumbar vertebrae

      Most massive

      Least mobile

      Subjected to great stresses

 

Sacrum

      Protects reproductive, digestive and urinary organs

      Articulates with pelvic girdle and fused elements of coccyx

 

Thoracic cage

      Thoracic vertebrae

      Ribs

      Sternum

    Ribs and sternum forms the rib cage

 

The ribs

      Ribs 1-7 are attached to vertebrae

      8-12 are vertebrochondral ribs

      11-12 are floating ribs

 

Typical rib

      Has a head, neck, tubercle and a body

      Costal groove marks pathway of blood returning to the heart

 

The Sternum consists of

      Manubrium

      Body

      Xiphoid process